void bubble_sort(int[][] arr, int n) {
    for (var i = 0; i < n-1; i = i+1;) {
        for (var j = 0; j < n-i-1; j = j+1;) {
            if ((arr[j][0] > arr[j+1][0]) |
                ((arr[j][0] == arr[j+1][0]) & (arr[j][1] < arr[j+1][1])) ) {
                var temp = arr[j+1];
                arr[j+1] = arr[j];
                arr[j] = temp;
            }
        }
    }
    return;
}

int longest_increasing_subsequence(int[] arr, int n) {
    var dp = new int[n];
    var max_subsequence = 0;

    for (var i = 0; i < n; i = i+1;) {
        dp[i] = 1;
        var max_seq = 0;
        for (var j = 0; j < i; j = j+1;) {
            if (arr[i] > arr[j] & dp[j] > max_seq) {
                max_seq = dp[j];
            }
        }
        dp[i] = max_seq + 1;

        if (dp[i] > max_subsequence) {
            max_subsequence = dp[i];
        }
    }

    return max_subsequence;
}

int max_envelopes(int[][] envelopes, int n) {
    bubble_sort(envelopes, n);

    var heights = new int[n];
    for (var i = 0; i < n; i = i+1;) {
        heights[i] = envelopes[i][1];
    }

    return longest_increasing_subsequence(heights, n);
}

int program(int argc, string[] argv) {
    var envelopes = new int[][] {
        new int[] {5, 4},
        new int[] {6, 4},
        new int[] {6, 7},
        new int[] {2, 3}
    };
    var n = 4;
    var res = max_envelopes(envelopes, n);
    return res;
}